This invention relates to an exhaust manifold for conducting exhaust gases from an engine block toward exhaust piping. In particular, this invention relates to an exhaust manifold having baffles arranged in a common space within the manifold to divide the space into a plurality of passageways thereby controlling the flow of exhaust gas through the manifold for engine performance tuning. More particularly, this invention relates to improved baffle configurations adaptable for single or dual exhaust manifolds.
Engine performance tuning is typically accomplished by means of an exhaust "header" type system. A conventional exhaust header comprises a plurality of individual elongated tubes for coupling each of the cylinder heads of an engine block to a remote manifold chamber of exhaust pipe. Adjacent exhaust ports in the engine block are "isolated" by the separate header tubes in order to tune engine performance. It is impractical to install header systems in many vehicles since these systems generally take up a significant amount of the small available space in the engine compartment. In addition, these header systems often require costly and complex welds and bends. See, for example, U.S. Pat. No. 4,373,331 to Santiago et al.
Conventional exhaust manifolds usually comprise heavy cast metal tanks coupled directly to the engine block in a position to receive engine exhaust gases. See, for example, U.S. Pat. No. 4,301,775 to Smart et al. The added weight provided by cast metal manifolds is known to affect fuel efficiency and hamper engine performance.
It is known to form an exhaust manifold using stamped sheet metal members. U.S. Pat. No. 4,537,027 to Harwood et al. discloses only an exhaust manifold of conventional configuration which has a housing formed of sheet metal construction.
U.S. Pat. No. 3,940,927 to Maurhoff et al. discloses a sheet metal shell containing a freely movable reactor chamber for afterburning engine exhaust gasses. The reactor chamber is freely movable within the shell in accordance with the thermal distortions of the reactor to minimize resulting stresses in the reactor. Maurhoff et al. does not address the problem of "tuning" an exhaust manifold.
U.S. Pat. No. 4,373,331 to Santiago et al. discloses a tubular manifold including two half-stampings welded together to form a plurality of separate exhaust tubes. A considerable amount of welding is necessary to join these two half-stampings together due to the tubular configuration of the Santiago et al. manifold. Also, the continuous webs interconnecting the exhaust tubes disclosed in Santiago et al. add additional weight to the manifold assembly. Although such a tubular design does not pemit "tuning" of the various runners, it does not provide the compactness required for many crowded underhood conditions.
One object of the present invention is to provide an exhaust manifold which eliminates complex welding and bending of tubes yet is configured to permit engine performance tuning.
Another object of the present invention is to provide a compact tuned exhaust manifold which is light weight, rigid, and easy to manufacture.
Yet another object of the present invention is to provide a stamped split exhaust manifold housing with drop-in baffles to divide a common space in the housing into a plurality of separate exhaust gas passageways configured to performance-tune the exhaust manifold.
Still another object of the present invention is to provide a method of assembling a tuned exhaust manifold which is simple and requires a minimum number of welded joints.
Another object of the present invention is to provide a manifold baffle configured and positioned relative to the manifold to permit easy attachment of the baffle to the manifold using welding equipment located outside of the manifold
Yet another object of the present invention is to provide improved means for anchoring a manifold baffle within its manifold housing to enhance stability and rigidity of the baffle during exposure to hot, turbulent exhaust gases in the manifold housing.
Still another object of the present invention is to provide baffle configurations adaptable for use in single and dual exhaust manifolds.
In accordance with the present invention, an exhaust manifold includes an inner shell providing a first flange having an interior and exterior surface and an outer shell cooperating with the inner shell to define an interior region therebetween. The outer shell provides a second flange having an exterior surface which is situated in spaced-apart relation to the interior surface of the first flange to form a flange-receiving space therebetween. The flange-receiving space provides an access opening into the interior region intermediate the inner and outer shells.
At least one baffle is situated in the interior region. The at least one baffle includes a mounting flange nested between the first and second flanges and positioned in the flange-receiving space to extend through the access opening so that a distal portion of the mounting flange is exposed to exterior surroundings outside of the interior region defined by the inner and outer shells. First attachment means is also provided for coupling the exposed distal portion of the mounting flange and adjacent exterior surfaces of the first and second flanges to anchor the at least one baffle in a predetermined position relative to the inner and outer shells at a first attachment site.
In one preferred embodiment of the present invention, the inner shell includes a bottom wall configured to provide inlet means for admitting combustion product into the interior region. The at least one baffle further includes flange means for engaging the bottom wall of the inner shell. The exhaust manifold further includes second attachment means for rigidly coupling the flange means to the bottom wall so that the at least one baffle is rigidly fixed to the inner shell at a second attachment remote from the first attachment site to anchor a second portion of the at least one baffle in a predetermined position relative to the inner shell, thereby fixing the at least one baffle securely in the interior region.
In other preferred embodiments of the present invention, the inner shell is formed to include inlet means for admitting combustion product discharged from an engine into the interior region. The inlet means has first and second sets of individual inlet openings, and first outlet means for exhausting combustion product from the interior region. The outer shell is formed to include second outlet means for exhausting combustion product from the interior region. In addition, the at least one baffle cooperates with the inner shell to provide first passageway means for conducting combustion product from the first set of inlet openings to the first outlet means and also cooperates with the inner and outer shells to provide second passageway means for conducting combustion product from the second set of inlet openings to the second outlet means. In this way, the at least one baffle is configured to provide a dual exhaust manifold.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art on consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.